(1) Field of the Invention
The present invention relates to a technology of transcoding video data received in digital broadcasting or the like to a different coding format.
(2) Description of the Related Art
In recent years, technologies for allowing people to view digital broadcast programs on mobile terminals as well as on television receivers have been proposed. For example, Japanese Laid-Open Patent Application No. 2001-285875 discloses a technology of transcoding an MPEG2 stream having been broadcast for television receivers to a low-resolution stream such as an MPEG4 stream.
When the necessity to reduce the ratio of occupying the apparatus discs and the necessity to reduce a time required to generate an MPEG4 stream from a received MPEG2 stream are taken into consideration, the transcoder is expected to have a construction shown in FIG. 1 in which the transcoder performs a streaming reproduction for television receivers in parallel with the transcoding from MPEG2 to MPEG4.
As shown in FIG. 1, after the transcoder receives an MPEG2 stream, a decompressing unit 80 decompresses compressed video data contained in the received MPEG2 stream, and outputs the decompressed video data to a first resizing unit 50 and a second resizing unit 60. The first resizing unit 50 converts the received video data to, for example, a resolution of 1,920 pixels×1,080 lines and 30 frames/second for HDTV (High-Definition TeleVision) receivers, and outputs the converted video data to television receivers or the like. In parallel with the operation of the first resizing unit 50, the second resizing unit 60 converts the received video data to, for example, a resolution of 360 pixels×240 lines and 10 frames/second for mobile terminals, and outputs the converted video data to a re-compressing unit 70. The re-compressing unit 70 compresses the received video data in compliance with the MPEG4 standard, and outputs an MPEG4 stream of the compressed video data. The MPEG4 stream is transferred to mobile terminals via the Internet or recording mediums.